Device and method for detecting electrically conducting objects to be measured in a ground

Abstract

A device (10) for detecting electrically conducting objects to be measured in a ground is provided, including a housing (21), a solenoid unit (34) situated in the housing (21), which includes a transmitter coil unit (38) and a receiver coil unit (39), a control unit (36), and an evaluation unit (37). A metal sheet (35) is provided in the housing (21), the solenoid unit (34) being situated on a lower side (53) of the metal sheet (35) facing the ground during the measuring operation, and the control unit (36) being situated on an upper side (54) of the metal sheet (35) facing away from the ground during the measuring operation.

The invention claimed is: 
     
       1. A device for detecting electrically conducting objects to be measured in a ground, the device being moved over a surface of the ground during the measuring operation in a measuring orientation, the device comprising:
 a housing; 
 a solenoid unit situated in the housing, the solenoid unit including a transmitter coil unit including at least one transmitter coil and including a receiver coil unit including at least one receiver coil; 
 a control unit connected to the solenoid unit and designed to control the transmitter coil unit and to control the receiver control unit; 
 an evaluation unit connected to the solenoid unit and designed to process and evaluate a voltage induced in the receiver control unit as a measuring signal; and 
 a metal sheet in the housing having a sheet metal thickness (d), the metal sheet being situated in parallel to the surface of the ground during the measuring operation, the solenoid unit being situated on a lower side of the metal sheet facing the ground during the measuring operation, and the control unit being situated on an upper side of the metal sheet facing away from the ground during the measuring operation. 
 
     
     
       2. The device as recited in  claim 1  wherein the evaluation unit includes a first evaluation unit processing the measuring signals, and a second evaluation unit evaluating the measuring signals, the first evaluation unit being situated on the upper side of the metal sheet facing away from the ground during the measuring operation. 
     
     
       3. The device as recited in  claim 2  wherein the second evaluation unit is situated on the upper side of the metal sheet facing away from the ground during the measuring operation. 
     
     
       4. The device as recited in  claim 2  wherein the second evaluation unit is situated outside the housing, the first and second evaluation units being connectable via a communication link. 
     
     
       5. The device as recited in  claim 2  wherein the housing encloses an interior, and the metal sheet divides the interior into a lower portion and an upper portion, the solenoid unit being situated in the lower portion, and the control unit and the first evaluation unit being situated in the upper portion. 
     
     
       6. The device as recited in  claim 1  wherein the housing encloses an interior, and the metal sheet divides the interior into a lower portion and an upper portion, the solenoid unit being situated in the lower portion, and the control unit being situated in the upper portion. 
     
     
       7. The device as recited in  claim 1  further comprising a display unit including a display designed to display a measuring result calculated by the evaluation unit, the display being situated on the upper side of the metal sheet facing away from the ground during the measuring operation. 
     
     
       8. The device as recited in  claim 2  further comprising a memory unit connected to the evaluation unit in a data-transmitting manner, a calibration signal being stored in the memory unit, the calibration signal having been ascertained in the absence of electrically conducting objects to be measured. 
     
     
       9. The device as recited in  claim 1  wherein the metal sheet is made of aluminum, the metal sheet having a sheet metal thickness (d) of at least 1.0 mm. 
     
     
       10. The device as recited in  claim 9  wherein the metal sheet has a sheet metal thickness (d) of at least 2.0 mm. 
     
     
       11. The device as recited in  claim 1  wherein the metal sheet is made of copper, the metal sheet having a sheet metal thickness (d) of at least 0.4 mm. 
     
     
       12. The device as recited in  claim 11  wherein the metal sheet has a sheet metal thickness (d) of at least 0.8 mm. 
     
     
       13. A method for detecting electrically conducting objects to be measured in a ground using the device as recited in  claim 11 , the method comprising a step sequence of the following steps:
 flowing a current (I) through at least one transmitter coil of the transmitter coil unit; 
 switching off the current (I) by the control unit at a switch-off point in time (t 0 ); 
 recording a voltage, induced in the at least one receiver coil of the receiver coil unit, by the evaluation unit with a time shift (Δt) after the switch-off point in time (t 0 ) of the current (I) as a measuring signal; and 
 determining a difference signal by the evaluation unit as a difference between the measuring signal and a stored calibration signal, the calibration signal having been ascertained in the absence of electrically conducting objects to be measured. 
 
     
     
       14. The method as recited in  claim 3  wherein the time shift (Δt) is not smaller than 5 μs. 
     
     
       15. The method as recited in  claim 3  wherein the time shift (Δt) is not greater than 10 μs. 
     
     
       16. The device as recited in  claim 1  wherein the housing has a lower housing shell and a housing cover enclosing an interior, the metal sheet being in the interior. 
     
     
       17. The device as recited in  claim 16  wherein the solenoid unit and the control unit are in the interior. 
     
     
       18. The device as recited in  claim 17  wherein the evaluation unit is in the interior. 
     
     
       19. The device as recited in  claim 16  further comprising a handle situated above the housing cover. 
     
     
       20. The device as recited in  claim 1  further comprising wheels connected to the housing.